This invention relates to catheters designed for insertion into bodily cavities of living beings, and more particularly to a new and improved design for multiple lumen diagnostic or therapeutic catheters.
The invention also relates to a method of constructing the catheter by assembling the outer and inner sleeves of the catheter, the balloon affixed to the outer sleeve, and a novel construction for a bushing which is positioned between the outer and inner sleeves of the catheter, in such a manner that the tip of the catheter is sealed more effectively and reliably than possible by other prior art construction methods.
Finally, the invention relates to a novel design for the bushing which is used in the construction, and which comprises part of the design, of the novel catheter.
Catheters are frequently used in conducting diagnostic and therapeutic procedures in bodily conduits. The catheter can be used to examine the conduits by injecting dye or similar detectable fluid into the conduit. The catheter can also be used to perform angioplasty procedures to widen the lumen of a coronary artery by inflating a balloon at the catheter tip, after it has been correctly positioned in an artery, thereby compressing stenotic lesions present within the artery. In addition to balloon catheters, laser catheters, other atherectomy catheters, and various diagnostic device catheters can also be used.
A typical angiographic or angioplasty procedure comprises inserting a catheter guided by a guidewire or other guiding means into the femoral artery of the patient, followed by a dilating balloon catheter which is guided to its intended position in the patient's cardiovascular system. Entering the femoral artery, the dilating balloon catheter is guided upwardly through the descending aorta, across the aortic arch, and down into the ascending aorta. The tip of the catheter is then inserted in the ostium of either the right or left coronary artery.
To make all of the required changes of direction within a patient's cardiovascular system, the catheter being used in the cardiovascular procedure must be capable of bending as well as twisting along its longitudinal axis as it travels through the arteries. And because it is important that the bending and twisting of the catheter not restrict the flow of liquids or gasses through any of the lumens of the catheter, nor hamper the movement of any guiding therapeutic or diagnostic means within a catheter lumen, it is important that the lumens remain unobstructed and substantially undeformed during the bending and twisting motion.
The cardiovascular application referred to above is an example of just one use for multiple lumen catheters. Multiple lumen catheters can be designed for and used in a number of other applications as well. Deformation of the lumens during manufacturing or use of multi-lumen catheters designed for a variety of uses is a problem which has faced many designers and users of the catheters.
One problem which has occurred in the construction of multiple lumen catheters is the sealing of the coaxial lumens disposed outside the central inner lumen, at the distal tip of the catheter, while at the same time keeping the outer lumens open and unobstructed. The problem occurs because balloons are frequently fastened to the outer tube of the catheter by thread winding under tension. The tensioned winding can restrict or close the outer lumen or lumens of the catheter, thereby making it difficult or impossible to inflate the balloon, if the balloon is inflated through one of the outer lumens, which is usually the preferred method for balloon inflation.